1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', 'ruq7d3mp4ia57in4ccp9ftphi2', '216.73.216.147', '1751756398', '1751756398', '/index.php?cat=c4_Beer-Mugs.html&XTCsid=2b50d004ceffb62515815b0230b19dd4')

[XT SQL Error]